Slide valve for hydraulic pressure systems

ABSTRACT

A slide valve for the control of high pressure hydraulic systems is provided which can be manufactured in a compact form for savings of space and production costs by virtue of having a pressure inlet port connected with first and second inlet apertures which are angularly offset in substantially the same cross-sectional plane of a valve housing having a longitudinally slidable valve member therein, with the first inlet aperture communicating through a transverse duct in the valve member with an exhaust (outlet) port of the housing when the valve member is in a neutral position, and the valve member having communication ducts formed therealong, advantageously as flat regions at opposite sides thereof interconnected by bores extending transversely therethrough at right angles to the aforesaid transverse duct, by which the second inlet aperture is connected with at least one pressure output or service port in the housing when the valve member is in a service position.

United States Patent 1191 Brunner et al.

[ SLIDE VALVE FOR HYDRAULIC PRESSURE SYSTEMS [75] Inventors: Rudolf Brunner, Baldham; Siegfried Zenker, Poing, both of Germany [73] Assignee: Heilmeier & Weinlein Fabrik fur Oil-Hydraulik KG, Munich,

Germany 22 Filed: Oct. 20, 1972 [21] Appl. No.: 299,300

[30] Foreign Application Priority Data Oct, 22, 1971 Germany... 2152830 52 us. c1. .Q 137/625/68 51 1111.01 Fl6k 11/07 [58 Field of Search 137/596, 596.12, 596.13,

[56] References Cited UNITED STATES PATENTS 2,951,505 9/1960 Hare 137/625.68 3,004,555 10/1961 Haberland 137/62568 3,194,265 7/1965 Tennis 137/596.12 3,346,012 10/1967 Williams 137/625.69

[ June 28, 1974 Primary ExaminerHenry T. Klinksiek Attorney, Agent, or Firm-Albert C. Johnston 1 ABSTRACT A slide valve for the control of high pressure hydraulic Systems is provided which can be manufactured in a compact form for savings of space and production costs by virtue of having a pressure inlet port connected with first and second inlet apertures which are angularly offset in substantially the same crosssectional plane of a valve housing having a longitudinally slidable valve member therein, with the first inlet aperture communicating through atransverse duct in the valve member with'an exhaust (outlet) port of the housing when the valve member is in a neutral position, and the valve member having communication ducts formed therealong, advantageously as flat regions at opposite sides thereof interconnected by bores extending transversely therethrough at right angles to the aforesaid transverse duct, by which the second inlet aperture is connected with at least one pressure output orservice port in the housing when the valve member is in a service position.

9 Claims, 11 Drawing Figures PATENTEDJUHZBJHM 3820.568 SHEET 1 OF 4 3 L5 T l h L1 FIG.2

1 SLIDE VALVE FOR HYDRAULIC PRESSURE SYSTEMS The invention relates to a slide valve used for control of high-pressure hydraulic systems, the housing of which has at opposite sides of thevalve bore a first inlet aperture for a pump connection and an outlet aperture for a pressureless circulation line and also has, offset in the longitudinal direction of the valve bore, at least one consumer connection with which there is associated a second inlet aperture connected to the pump connection, and in the valve member of which there is formed at least one communicating duct for connecting the consumer connection with the second inlet aperture and a transverse communication duct, controlled in the opposite sense thereto by displacement of the valve member, for connecting the first inlet aperture to the outlet aperture of the pressureless circulation line.

A slide valve is already known which can be adjusted between a position for pressureless throughflow and respective connection positions to a consumer connection of a consumer having two connections. The throughflow duct for pressureless throughflow is axially offset and is situated in the form ofa peripheral notch outside the two consumer connections (BOSCH- I-Iydraulia, Information und Daten 1970/71, Page 80, 4.2).

In a further known slide valve the pressureless circulation duct is arranged centrally. From this duct two inlet ducts branch to in each case a consumer connection, these being situated opposite their inlet duct in each case in axially offset planes. Also the duct constructed as a peripheral groove for pressureless circulation comprises a change of direction (Hamworthy Hydraulics Ltd, Installation Sheet, 12 480 4, Page 1, April 1967. I

Finally, it is also known in a quantity-regulated control valve to arrange an auxiliary duct in the same cross-sectional plane as a main duct (Federal German Utility Model 1,968,337).

Owing to the duct arrangement, a very considerable overall lengthis required in the case of the known slide valves. As is known, slide valves of the type specified are used in arrangements whose construction aims at having a compact form as an essential feature. Therefore, reducing the overall length of the slide valve means a considerable saving in space. Furthermore,

with reduced overall length, the production costs of slide valves can be substantially reduced, which means considerably'increased sales possibilities with the competitiveness of the present-day market.

Therefore, the object of the invention is to provide a slide valve of the type specified initially whose overall length can be substantially reduced as compared with known slide valves.

This object is achieved in a slide valve of the type cation duct cross one another substantially at right angles in the same transverse plane of the valve without intersecting.

To obviate pressure surges, conveniently a nonreturn, or check, valveis arranged between the second inlet aperture and the inlet duct coming from the pump connection.

A particularly advantageous constructional form consists in that the communication ducts arranged at opposite sides of the valve are connected by bores.

Construction is simplified if the communication ducts consist of shallow recesses in the valve member, which are situated in the region of the communication bores.

Instead of a single consumer connection for a singleacting consumer, it is also possible to provide a double connection for a double-acting consumer. This is effected by two consumer connections arranged in the longitudinal direction of the valve at the two sides of the pump connection, these consumer connections being adapted to be brought separately from one anspecified in that both the first and the second inlet ap- I ertures are arranged substantially in the same crosssectional plane of the slide valve, and that the transverse communication duct is constructed as a through bore in the valve member.

duction in manufacturing costs but at the same time also opens up a wide range of applications hitherto other each into communication with the pump connection.

In order to keep the force required for displacement of the valve member within limits even at the maximum pressure, in a preferred arrangement there are provided in the same cross-sectional plane of at least one slide valve two parallel bores arranged adjacent one another of which one forms the transverse communication duct and the other a continuation of the inlet duct continued to the return flow connection, in which the direction of flow of the pressure fluid is directed oppositely to the direction of flow through the transverse communication duct.

According to the invention the possibilities of using the slide valve can be extended by using a number of valve members whose second inlet aperture is branched off from the inlet duct in parallel manner and which are so arranged in the housing that a through transverse communication duct can be adjusted.

Constructional forms of the invention will be explained in detail with the help of the accompanying drawings.

FIG. 1 shows a sectional view through a slide valve according to the invention for a single-acting consumer. I

FIG. 2 shows a section along the line IIII of FIG. 1.

FIG. 3 shows in section along the line III-III of FIG. 1 the valve member in the case of pressureless delivery.

FIG. 4 shows in a view similar to FIG. 3 the valve member in the operative position.

FIG. 5 shows in a view similar to FIG. 3 a valve member for a double-acting consumer.

FIG. 6 shows in a view similar to FIG. 2 an arrangement with two valve members, with approximately uniform pressure application.

FIG. 7 shows in a view similar to FIG. 1 two valve members arranged one behind the other in a housing.

FIG. 8 shows a section along the line VIII-VIII of FIG. 7.

FIG. 9 shows a section along the line IX-IX of FIG. 7.

FIG. 10 is a longitudinal cross-sectional view, and FIG. 11 a transverse cross-sectional view, of a further embodiment of the invention.

The slide valve shown in FIGS. 1 to 4 comprises a housing 1 with a valve bore 2 for receiving the slide valve member 20. The housing 1 can be produced as a casting with suitable sub-division or can be manufactured as a housing with the necessary covers. For particularly high pressures, however, there is used a block in which the appropriate bores or passages are provided which are closed at the appropriate places by blind plugs and are reduced in their diameter by the insertion of bushings. The sealing elements which are inserted in the valve and guarantee sealing-tight displacement, have not been shown in the drawings, with a view to simplification.

Provided at one side in the housing 1 is a pump connection 3 with an appropriate screwthread. The pump connection 3 opens on the one hand into a first inlet aperture 8 and an inlets duct 14 which branches off at right angles to the first inlet aperture 8 and is made to follow a U-shaped course in the same plane to open by way of a non-return valve 15 and a second inlet aperture 13 into the communication duct 4 of the valve member 20. The communication duct 4, as FIGS. 2 and 3 show, is in the form of a shallow recess. The communication duct 4 has situated opposite it at the other side of the valve member a similarly shaped communication duct 5, the communication ducts 4 and 5 communicating with one another through communication bores 6 and 7. Between these connections, the valve member has a transverse communication duct 12 formed through it at right angles to the said connections, said transverse communication duct, in the valve member position shown in FIG. 1, being in alignment with the first inlet aperture 8 proceeding from the pump connection 3, and at the opposite valve member side with the outlet aperture 9, the outlet aperture 9 opening into the return flow connection 10 which is provided with a suitable screwthread. As more especially FIG. 2

shows, the inlet duct 14, the second inlet aperture 13,

the first inlet aperture 8 and the outlet aperture 9 are situated in the same cross-sectional plane. The valve member is operated mechanically, electrically, hydraulically or pneumatically by suitable means through the agency of a rod 11 projecting from the housing 1. Arranged in the housing about the valve member bore 2, at the side opposite from the valve member rod guide, is an annular conduit 16 which opens into a consumer connection 17 with a suitable screwthread, the consumer connection 17 debouching at a side of the housing 1 which is adjoined by the sides with the pump connection 3 and return connection 10.

The spacing between the annular conduit 16 and the second inlet aperture is made such that the communication duct 4 or 5 in the valve member position shown in FIG. 4 establishes a communication between the sec- 0nd inlet aperture 13 and the annular conduit 16 i.e., the consumer connection 17, whereas in the position shown in FIG. 3 this communication is discontinued and instead pressureless delivery is effected through the first inlet aperture 8, the transverse communication duct 12, the outlet aperture 9 and the return flow connection l0.

Owing to the fact that the communication ducts 4 and 5 are situated at opposite sides of the valve member, connected by the communication bores 6 and 7, sufficiently large flow cross-sections are available. The valve member bore space 2 at the valve member rod side which is bounded by the upper face of the valve member 20, has a means for supplying and removing air which is not shown here and can communicate for example with the oil return 10. If desired, there can be provided for the return of the valve member into the position shown in FIG. 3 an elastic element in the form of a compression spring arranged between the bottom of the valve member bore 2 and the valve member face which is opposite from-the rod 11.

The non-return valve 15 which can be provided optionally opens only when the pressure prevailing in the inlet duct 14 has reached a specific value. At the same time the non-return valve obviates the reaction of pressure surges which could act by way of the return connection 10.

The slide valve shown in FIGS. 1 to 4 in the position corresponding to FIGS. 1 to 3 operates in such a manner that the pressure fluid delivered by the pump is supplied through the pump connection 3, via the first inlet aperture 8, the transverse communication duct 12, the outlet aperture 9 and the return flow connection 10 in pressureless manner, whereby a kind of bypass effect is provided. On displacement of the valve member into the position shown in FIG. 4 the communication of the transverse communication duct 12 with the first inlet aperture 8 and the outlet aperture 9 is interrupted. At the same time a connection is established between the pump connection, the inlet duct 14 and the second inlet aperture 13 with the communication duct 4, which is connected via the communication bores 6 and 7 to the communication duct 5. Whereas the communication duct 4 opens into the annular conduit 16, the communication duct 5 opens into the part of the annular conduit which continues directly into the consumer connection 17. Thus in this position, which is to be regarded as the operative position of the valve member, a connection is established between the pump connection 3 and the consumer connection 17. The pressure fluid flows to the consumer from one direction and is returned .to the pump via a return line which is not shown.

The slide valve shown in FIG. 5 is suitable for doubleacting consumers in that in planes above and below the cross-sectional plane in which the inlet duct 14, the second inlet aperture 13, the first inlet aperture 8 and the outlet aperture 9 are situated, annular ducts l6 and 18 respectively are provided which open into consumer connections 17 and 19. In order that the communication ducts 4 and 5 can be brought into communication with the annular conduits 16 and 18 respectively, 2a suitably deep bore 2 is provided. In the arrangement shown in FIG. 5, the valve member 20 is in the bypass position i.e., the pressure fluid delivered by the pump flows through the first inlet aperture via the transverse communication duct to the return connection 10.

. When the valve member is displaced into an operative position in which the communication ducts 4 and 5 connect with the annular conduit 16, the annular conduit 18 is in communication with the part of the bore 2 in the valve member rod region. For the pressure fluid collecting therein, either a suitable discharge can be-provided or the passage system consisting of consumer connection 19, annular conduit 18 and upper part of the bore 2 is used directly as a return passage for the fluid coming from the consumer. In the opposite valvemember position, such a connection is provided via the consumer connection 17, the annular conduit 16 and the lower portion of the valve member bore. If the consumer is for example a reciprocating piston, conveniently the upper and lower portions of the bore will be constructed as return conduits and brought together at a suitable point,

A constructional form of this kind is shown in FIGS. 7 to 9 wherein two valve members are arranged one behind the other, the first valve member 20A corresponding to the constructional form shown in FIGS. 1 to 4 and the second valve member 205 to the constructional form shown in FIG. 5. The valve members are so arranged that when both are brought into the bypass position the first inlet aperture 8a, the particular transverse communication ducts 12a and 12b and the particular outlet apertures 9a and 9b are arranged in align-v ment, the outlet aperture 9 of the first valve member 20A being at the same time the first inlet aperture of the second valve member 208. As FIG. 8 shows, the second inlet apertures 13A and 138 respectively branch off in parallel from the inlet duct 14a and in the illustrated constructional form a non-return valve is simply arranged between the second inlet aperture 13A of the first valve member 20A and the inlet duct 14a, whereas the branch from the inlet duct into the second valve member 20B opens directly into the second inlet aperture 138. The arrangement of the non-return valve depends on the particular use intended, i.e., it may be provided before none of the second inlet apertures 13A, 1313, or upstream of only one of them, or of both of them.

FIGS. 7 and 9 show clearly an arrangement for the return flow described with reference to FIG'. 5. A lower duct 23 is provided which in the appropriate valve memberposition can be brought into communication with the particular consumer annular conduit of the valve members. Also an upper duct 22 is provided which in the illustrated example can be brought into communication with the upper annular conduit of the valve member 20B. The ducts 22 and 23 and also the outlet aperture 96, of the second valve member 20B open into the return connection a.

In the constructional form shown in FIG. 6, a view similar to FIG. 8, the inlet duct 14b from which the second inlet apertures branch off via non-return valves A and 15B, is continued so that it extends as the duct 25 parallel to the transverse communication duct 12b through the valve members A and 20B and then is continued outside the valve members into the return connection 10b. Thus, two parallel bores extend through the valve members in offset manner relatively to a longitudinal central plane, the object being to make the pump pressure act from different directions on the valve member and thus to provide compensation so that displacement is possible without great expenditure of force more especially at very high pressures.

The small lever arm because of the eccentric arrangement of the ducts 12b and 25 respectively causes only a very small moment which can easily be compensated by a suitable bearing arrangement.

FIGS. 10 and 11 show a longitudinal section and a cross-section of a practical embodiment through a slide valve according to the invention. The cross section of FIG. 11 extends along the axis of the right-hand valve member seen in FIG. 10.

The housing generally indicated by reference numeral 10 comprises a housing block on which a lever housing is mounted at a longitudinal side thereof. A first housing cap 132 is mounted at the other longitudinal side thereof, while a second housing cap 134 is mounted at one front surface thereof and annular sealing elements 136, 138 and 140 provide for sealing against the ambience. The lever housing 130 and the first housing cap 132 are clamped on the housing block 110 by first clamping studs 142 which extend from the first housing cap 132 through bores (not shown) in the housing block 100 into bores (not shown either) in the lever housing, and in the said lever housing are either engaged in a screwthread or extend through the housing and are clamped on'the opposite side. Ina similar manner the second housing cap 134 is mounted on the housing block 100 by three second clamping studs 144 which are engaged in bores 146 in the block.

The housing block 100 is provided, between its two longitudinal sides, with two parallel bores 148 and 150 which open on the two longitudinal sides of the housing block 100 and in each of which a substantially cylindrical slide valve 120a and 120b respectively is sealingly displaceable in longitudinal direction. Each valve member has a forked extension 152 on its end facing the lever housing 130, and respective actuating rods 154a and 154b are pivotally mounted on the said extensions through hinge rods 156. The other end of each actuating rod extends outwardly of the lever housing 130 through a gasket 158 and a jammed-in end plate 160 and carries a first shaft 162. One end of a bi-partite couple 164 is hingedly mounted on the said shaft, while its other end is hingedly mounted on a second shaft 166 which forms a hinge connection with a tapered end of an actuating lever 168. This lever is adapted to be pivoted around an arbor 170 of a bearing block 172 rigidly connected to the lever housing.

Both Figures show the neutral position of the valve members 120a and 120b. Each valve member may be displaced axially from this neutral position in both directions into an operating position, by pivoting lever 168 upwardly or downwardly in each case against the force of a double-acting return spring 174. The upper end of the spring 174 as seen in the drawing is supported on a projecting edge of a substantially cupshaped firstengaged member 176 when a downward displacement is. effected as seen in the drawing, this first engaged member being carried along by a shoulder extension 152.

The housing block 100 is provided with a pump connection 103, a return flow connection 110, a single consumer connection 117a on the first valve member 120a and two consumer connections 1171) and 11% on the second valve member 120b. From this it becomes evident that the single-acting valve member 120a and the double-acting valve member 120b are combined in the same housing block 100. I

As shown in FIG. 11, the pump connection 103 opens laterally within a non-return valve 115 closing in the direction of the pump; this valve 115 has a valve body 184 jammed into a bore on the side of the housing block which is opposite to the consumer connections, and holds, on a transverse stud 186, a tension spring 188 which tries to hold a valve cap 190 at a valve seat 192 against the opening of a valve chamber 194 spared in the valve body 184. The pump connection 103 opens into this valve chamber.

The non-retum valve 115 connects the pump connection 103 with a respective first inlet aperture to the respective valve member, the first inlet aperture 1081) leading to the second valve member 12% being shown in FIG. 11. The inlet aperture 108b and the corresponding inlet aperture (not shown) of the other valve member 120a open each into a communication duct which in FIG. 11 is indicated by 104b for the valve member 120a and is designed as a flat recess in the respective valve member, i.e., here in valve member 1201). On the other side of the valve member the communication duct is opposed by another communication duct also designed as a flat recess, as shown in FIG. 11 by means of the communication duct 105b. Both communication ducts are interconnected by communication bores in the respective valve member. In the case of valve member 120a a single communication bore 106a is provided which is axially displaced relative to the first inlet aperture when the valve member is in its neutral position. In the case of the second valve member 1201; two respective communication ducts 1061) and 107b are provided, namely also displaced relative to the first inlet aperture 108b, but disposed symmetrically to the opposite side of the latter when the valve member is in its neutral position. It should be noted, however, that also with the double-acting valve member 12% only a single communication bore need be provided, or in the case of the first valve member 120a several communication bores, without impairing the principle of operation. However, the arrangement which has been illustrated has practical advantages in fluid flow.

A first inlet passage 114 branches off frornthe f rst inlet aperture 108!) at right angles and leads to a second inlet aperture 113a again branching off from that passage at right angles and being connected to the first inlet aperture in a U-shape. In the housing block 100 a second inlet aperture l13b extends to the second valve member 120b in alignment with the second inlet aperture 113a. On the other side of the valve member 12% there follows an outlet aperture 109 in the housing block 100 which again is in alignment with this second inlet aperture 113b. The outlet aperture 109 opens into a chamber 196 of the second housing cap 134. The chamber 196 is connected with a further chamber 202 in the first housing cap 132 by means of a crossintersecting channel 198 in the housing block 100 and an enlarged end 200 of the bore 150 receiving the valve member 12%. The chamber 202 communicates, on the one hand, with that end of the bore 148 in the housing block 100 which does not face the lever housing (bore 148 being adapted to receive the valve member 120a), and on the other hand with the return flow connection 1 10 in the housing block through a communication bore 204. It is obvious that the return flow connection as well as all other fluid connections is provided with outwardly directed threaded connections 206 or other connecting means.

The inlet passage 114 is additionally connected, from the side of the lever housing 130, with a safety valve of a conventional construction which is generally designed by 208 and the detailed description of which is irrelevant to the mode of operation of the invention and therefore can be disregarded.

Another return line 210 is provided in parallel to the cross-intersecting channel 198 in the housing block 100 and connects the chamber 196 in the second housing cap 134 with the front surfaces of the valve members a and 120)) which are provided adjacent the lever housing 130. Any working fluid leaking through the safety valve 208 will flow to the return line 210 through a chamber 212 in the lever housing and through the enlarged ends of bores 148 and 150 in the housing block 100 which are connected to this chamber 212. Hereby, the lever housing will always be relieved of pressure.

In the neutral position of both valve members 120a and 120b as shown in FIGS. 10 and 11 the second inlet aperture 113a is in alignment with the transverse duct 112a in the valve member 120a and the second inlet aperture l13b is in alignment with the transverse duct 11211 in the valve member 120b. This transverse duct 1l2b is a single bore having enlarged ends (see FIG. 10) anda greater extension between the two sides of the valve member 12% than in the axial direction thereof. Instead, the transverse duct 112a is subdivided into several individual bores 214 parallel to one another and succeeding each other along the valve member axis so as to better cover the connecting surface; the individual bore 214 which is next to the communication bore 106 is also enlarged additionally at its both ends.

The consumer connections 117a, 117b and 11% are each connected to opposite recesses 216 and 218 in the housing block 100 which communicate with one another through connecting grooves 220 so as to obtain a pressure relief of the respective valve member 120a and l20b. I

Incidentally, it can be seen that in accordance with the invention both the first inlet aperture 108a and 108b respectively and the second inlet aperture 113a and ll3b respectively are angularly displaced in a cross-sectional area which is closely limited axially, namely even in the same cross-sectional plane on the housing block 100 and between two consumer connections 117b and 11% provided in the case of the valve member 12% and that, furthermore, the respective transverse ducts 112a and 112b are designed as radial through-holes in the respective valve members 120a and l20b which in their neutral position or midposition are in alignment with the respective first inlet apertures 108a and 108b and with the outlet aperture 109. Moreover, the respective transverse ducts 112a and 112b and the respective communication ducts 104 and 105 and the communication bores 106a, 106b and 107b connected thereto extend substantially at right angles to one another without intersection.

The effect is the following:

In the neutral position of both valve members 120a and 120]) shown inthe Figures a pressure-relieved circulation is effected in the bypass from the pump connection 103 through the non-return valve 115, the second inlet aperture 113a, the transverse duct 112a, the second inlet aperture 113b, the transverse duct 112b, the outlet aperture 109, and the chambers 196 and 202 to the return flow connection 110.

When displacing one of the valve members 120a and 1120b respectively into the operating position by correspondingly actuating the respective actuating lever 168 the bypass is closed, and instead the respective first inlet aperture, for instance, the first inlet aperture 108b, is connected, through the communication duct 106a or the communication ducts 106b and 107b, to

the consumer connection 117a, ll7b or 11%. In the case of the double-acting valve member 120k the respective other consumer connection is connected to the return line through one front surface of the valve member. In the case of the single-acting valve member 120a the communication of the single consumer connection 117a with the return line is effected, by reverse displacement of the valve member 120a by means of the respective actuating lever 168, through a connection to the chamber 202 via the end of the valve member bore 148 which is remote from the lever housing 130. To this effect, the end of the valve member 120a should be provided with a leading edge 222 to achieve precise control (see FIG.

I claim:

1. Control valve of longitudinal slide valve type for the control of hydraulic consumers, having a pressureless circulation arrangement passing centrally through the bore which houses the valve member in the neutral position of the control valve via a first inlet aperture connected with a pump connection and via an outlet aperture, also having at least one consumer connection offset in the longitudinal direction of the valve member bore with which connection there is associated a second inlet aperture connected to said pump connection, and also having at least one communication duct provided in the valve member for connecting the consumer connection with the second inlet aperture and having a transverse communication duct adapted to be brought into operation in the opposite sense by displacement of the valve member, for connecting the first inlet aperture with the outlet aperture of the pressureless circulation arrangement, characterised in that both the first and the second inlet apertures are arranged in angularly offset manner in a narrowly limited arial region of the valve member, and that the transverse communication duct is constructed as a radial through-bore in the valve member, which in the neutral position of the control valve is in alignment with the first inlet aperture and the outlet aperture.

2. Control valve according to claim 1, characterised in that the transverse communication duct and the communication duct are arranged in the same crosssectional plane of the valve member.

3. Control valve according to claim 1, characterised in that the transverse communication duct and the communication duct extend substantially at right angles to one another without intersecting.

4. Control valve according to claim 1, characterised in that between the second inlet aperture and the inlet duct coming from the pump connection there is arranged a non-return valve.

5. Control valve according to claim 1, characterised in that there are two said communication ducts which-as viewed in radial sectionare situated at opposite sides of the valve member and are connected to one another by communication bores. 7 i 6 Control valve according to claim 1, characterised in that the communication ducts comprise shallow recesses provided in the valve member in the region of the communication bores.

7, Control valve having at least one slide valve member according to claim 1, characterised in that in one and the same cross-sectional plane of at least one valve member there are provided side by side two parallel bores of which one bore forms the transverse communication duct and the other bore provides a communication between the inlet duct and the return connection via a duct in the valve housing, the flow of the pressure medium in said other bore being directed oppositely to the'direction of flow through the transverse communication duct.

8. Control valve having -a plurality of slide valve members according to claim 1, characterised in that the particular second inlet aperture leading to the valve members branches off in parallel manner from the inlet duct, and that the valve members are so arranged in the housing that the first inlet apertures, the outlet apertures and the transverse communication ducts of all the control 'valves are in alignment with one another.

9. Control valve according to claim 1, wherein there are two of said consumer connections and said axial region lies between said consumer connections.

. l l= =l UNITED STATES PATENT OFFICE CERTIFICATE or CORRECTION Patent No. 3,820,568 Dated June 28, 1974 Inventors: RUDOLF BRUNNER and SIEGFRIED ZENKER Assignors to Heilmeier & Weinlein Fabrik fur Oel-Hydraulik KG, Munich, Germany,

It is certified that errors appear in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:

Heading at [73] "Oil" should read -Oel Beneath the Abstract, "9 Claims" should read -].0 claims--. Column 1, line 36, "1967, should read -l967) Column 4, line 63, in place of "2a" read a.

Column 4, line 64, in place of "2" read 2a--. Column 5, line 28, in place of "9" read -9a--. Column 5, line 52, in place of "96" read 9b--. Column 6, line ll, in place of "'10" read lD-.

Column 7, line 38, in place of "side" read -sides 7 Column 10, the following claim 10 should appear in the patent after claim 9:

- 10. A longitudinal slide valve for the control of hydraulic consumers, having a pressureless circulation arrangement which in a neutral position of the valve passes centrally through a bore that houses a slidable valve member via a first inlet port connected with a pumpconnection and via an outlet port, and havi two consumer ports respectively spaced from said outlet port at opposite sides thereof in the longitudinal direction of said bore and each adapted to be connected with a second inlet port connected via an inlet duct to said pump connection, said valve member having therein two communication ducts respectively for connecting either of said consumer ports with said second inlet port upon a longitudinal displacement of said valve member and having therein a transverse duct rendered operative by displacement of said valve member in the opposite direction for connecting said first inlet port with said outlet port, characterized in that said first and second inlet ports are angularly spaced apart in a limited longitudinal region of said valve member and said transverse duct is a bore extending radially through said valve member and which in said neutral position is aligned with said first inlet port and said outlet port, said transverse duct and said communication ducts being located in a common plane transverse to said valve member and respectively extending substantially at right angles to one another without intersecting, said communication ducts respectively comprising shallow recesses formed in and along the periphery of said valve member at opposite sides thereof and being interconnected by communication bores extending transversely through said valve member at opposite sides of and substantially at right angles to said transverse duct, said limited longitudinal region lying between said consumer ports, and a check valve in said inlet duct from said pump connection to said second inlet port.

Signed and. sealed this 8th 'day of October 1974 (SEAL) "attest: I

McCOY M. GIBSON JR. Co MARSHALL DANN Attesting Officer I Commissioner of Patents 

1. Control valve of longitudinal slide valve type for the control of hydraulic consumers, having a pressureless circulation arrangement passing centrally through the bore which houses the valve member in the neutral position of the control valve via a first inlet aperture connected with a pump connection and via an outlet aperture, also having at least one consumer connection offset in the longitudinal direction of the valve member bore with which connection there is associated a second inlet aperture connected to said pump connection, and also having at least one communication duct provided in the valve member for connecting the consumer connection with the second inlet aperture and with a transverse communication duct adapted to be brought into operation in the opposite sense by displacement of the valve member, for connecting the first inlet aperture with the outlet aperture of the pressureless circulation arrangement, characterised in that both the first and the second inlet apertures are arranged in angularly offset manner in a narrowly limited arial region of the valve member, and that the transverse communication duct is constructed as a radial through-bore in the valve member, which in the neutral position of the control valve is in alignment with the first inlet aperture and the outlet aperture.
 2. Control valve according to claim 1, characterised in that the transverse communication duct and the communication duct are arranged in the same cross-sectional Plane of the valve member.
 3. Control valve according to claim 1, characterised in that the transverse communication duct and the communication duct extend substantially at right angles to one another without intersecting.
 4. Control valve according to claim 1, characterised in that between the second inlet aperture and the inlet duct coming from the pump connection there is arranged a non-return valve.
 5. Control valve according to claim 1, characterised in that the communication ducts - as viewed in radial section - are situated at opposite sides of the valve member and are connected to one another by communication bores.
 6. Control valve according to claim 1, characterised in that the communication ducts comprise shallow recesses provided in the valve member in the region of the communication bores.
 7. Control valve having at least one slide valve member according to claim 1, characterised in that in one and the same cross-sectional plane of at least one valve member there are provided side by side two parallel bores of which one bore forms the transverse communication duct and the other bore provides a communication between the inlet duct and the return connection via a duct in the valve housing, the flow of the pressure medium in said other bore being directed oppositely to the direction of flow through the transverse communication duct.
 8. Control valve having a plurality of slide valve members according to claim 1, characterised in that the particular second inlet aperture leading to the valve members branches off in parallel manner from the inlet duct, and that the valve members are so arranged in the housing that the first inlet apertures, the outlet apertures and the transverse communication ducts of all the control valves are in alignment with one another.
 9. Control valve according to claim 1, wherein there are two of said consumer connections and said axial region lies between said consumer connections. 